Acebal de Garagüeta, Holly forest nature reserve in Arévalo de la Sierra, Soria, Spain

Acebal de Garagüeta is a natural reserve of 406.4 hectares in Arévalo de la Sierra, Soria, within the Sierra de Montes Claros. About 180 hectares form a dense, continuous mass of holly (Ilex aquifolium) whose branches interlace into vaulted galleries called sestiles, with clearings and mountain pastures between them.

The reserve gained official protection status in 2008 through regional legislation designed to preserve its ecological significance. This designation recognized that this particular forest type had become increasingly rare in the region.

The name sestiles for the holly vaults is linked to siesta, as the sheltered shade was traditionally used for rest. Local livestock farming and the regulated collection of ornamental holly branches have shaped the woodland, and the reserve lies in Arévalo de la Sierra, in the Almarza district.

Access to the reserve begins by taking the N-111 road toward Almarza and continuing toward Arévalo de la Sierra, where an information center offers maps and guidance. From there, visitors can explore marked trails throughout the forest.

The holly canopies form vaulted shelters called "sestiles", a term linked to the Spanish siesta, where cattle and wildlife rest. Inside them the air stays about 5 °C different from outside, cooler in summer and milder in winter.